Crestbond shear connector for load transfer on concrete filled composite columns in fire

ABSTRACT: This paper presents a numerical study of the Crestbond shear connector, characterized by a steel plate with regular cuttings, when used as a load transfer element in concrete filled composite columns in fire. The developed numerical model was calibrated with experimental results of composite columns in fire and later the load transfer devices were inserted. Numerical analyzes were performed with the software Abaqus and comprised the variation of the composite column diameter and of the loading levels, as well as the comparison with the results obtained when is used a through steel plate without cuttings (Shear Flat) as a load transfer device. With the analyzes performed, it was observed that the Crestbond shear connector and the Shear Flat present very similar thermomechanical performance in relation to the load transfer capacity. Thus, the Crestbond shear connector has the potential to be applied alternatively to the Shear Flat as a load transfer device in concrete filled composite columns, with the advantage of the possibility of associate use of longitudinal and manly transverse reinforcement.

Parameters Optimization and Energy Absorption Evaluation of the Steel Ball Friction Energy Absorber

The energy absorber is used to simulate the reaction of a working piece subjected to a vibration stimulus, by which the consistent and repeatable reactions to the tool’s vibration inputs could be achieved. According to the proposed coupling simulation model by using commercial software RecurDyn and EDEM, the energy dissipated by the energy absorber and the contact force between the drill rod and the piston are evaluated under different load conditions such as the impact frequency and impact stroke. Moreover, the effects of the ball diameter, ball column height, and diameter on the energy absorption characteristics are also studied. The results show that the impact frequency and stroke influence the energy absorber by changing the impact force; the energy absorption is more obvious under higher impact frequency and long impact stroke. The filling ball diameter influences the energy reflectivity by changing the porosity, which is negatively correlated to the energy reflectivity, and a 6 mm filling ball diameter is suggested. The energy reflectivity is inversely proportional to the ball column height and diameter, and the suggested ball column diameter and height are 160 mm and 600 mm, respectively, with energy reflectivity of 0.045. Even when the increase in impact frequency and stroke will increase the contact force, the dynamic load factor decreases. The contact force and dynamic load factor are inversely proportional to the ball column height, but they are not influenced by the ball diameter and the ball column diameter.

Mechanical Properties and UV Reliability of Microlattice with Urethane Elastomers for insole

We investigated the properties of architected materials made from UV-cured urethane elastomers and the use of such materials for insoles. The durability and reliability of various materials currently used in medical insoles were compared with those of architected materials with microlattice. The results show that architected materials made from UV-cured urethane elastomers have high impact resilience and grip, and the hardness can easily be changed by adjusting the column diameter of the unit cell. Compared with the foam materials used for medical insoles today, these architected materials also demonstrate superior UV resistance, suggesting that, after being washed in water, they can be air-dried outdoors.

Peningkatan Daya Dukung Pondasi pada Tanah Lempung dengan Perkuatan Kolom Tanah

One of the problematic soils for construction if the soil is used as a foundation for a construction is clay soil which has relatively low shear strength and bearing capacity. Therefore, it needs an improvement effort to increase the strength of the clay soil. The reinforcement soil column is an alternative effort to improve the soil. This paper presents the results of laboratory-scale experimental on the reinforcement modelling of clay soil columns mixed with 6% rice husk ash (RHA). Modelling was carried out with 6 variations of column groups with constant column length of 67cm. The first three variations are the variation in the distance between columns (s/d) with a fixed diameter of 8 cm. The other three variations are column diameter variations with a fixed s/d ratio. The results showed that the larger the distance between the columns, the smaller the bearing capacity of the soil foundation. If the s/d ratio is constant, it is found that the larger the column diameter, the greater the bearing capacity of the soil foundation. The maximum ultimate bearing capacity of the soil is achieved in variations with a column diameter of 12cm and a distance between columns of 30cm (s/d = 2.5) with a value of 39.56 kPa. This bearing capacity provides a BCR value of 3.75% or almost 4 times the bearing capacity of the unreinforced foundation.

Experimental Study on the Seismic Performance of Socket Bridge Piers

In order to accelerate the construction of bridge substructure, a socket joint construction that does not require interfaces roughening between the precast columns and the reserved cavity of the precast foundation is raised in this paper. The seismic performance of such fabricated bridge piers was investigated by carrying quasistatic tests on socket circular pier specimens of different embedment depths with a compared cast-in-place pier specimen. The experimental results showed that the prefabricated piers with the embedment length larger than 1.0 times the column diameter, featuring smooth interfaces that was free of roughening, had a failure mode of bending damage as well as the cast-in-place component. As the embedment depth increases, the seismic performance indexes of the socket bridge pier, including bearing capacity, ductility, and energy dissipation capacity, are improved. The seismic performance indexes of a socket bridge pier specimen with an embedment depth of 1.5 times the column’s diameter in the test are better than the cast-in-place one.

A Study of Fluctuation and Expansion Ratios for Gas-Solid Fluidized Columns

The fluctuation and expansion ratios have been studied for cylindrical gas-solid fluidized columns by using air as fluidizing medium and Paracetamol as the bed material. The variables were the column diameter (0.0762, 0.15, and 0.18 m), static bed height (0.05, 0.07, and 0.09 m), and air velocity to several times of minimum fluidization velocity. The results showed that both the fluctuation and expansion ratios had a direct relation with air velocity and an inverse one with column diameter and static bed height. A good agreement was between the experimental results and the calculated values by using the correlation equations from the literature.

Surface Topography and Grain Morphology of Nanolayer TiAlN/TiSIN Coating Governed by Substrate Material and Rotation during Deposition

Nanolayer TiAlN/TiSiN coating is one of the most advanced contemporary protective coatings. It has been applied for protection of machining tools, forming tools, and die casting tools. However, due to its versatile properties, there is a high potential for broadening its application; for example, for protection of biomedical implants. Each application requires specific base materials, for example cold working steels are used for forming, while stainless steels are applied for biomedical purposes. Different materials and their pre-treatment might result in different coating properties even if coating was conducted in a single batch. Real tools and components have complex geometries, and as such require a multiple-axis rotation during the deposition. Among other properties, grain morphology and surface topography are of great importance in a real application. Since systematic studies on the effect of substrate materials and rotation during deposition on these properties are very scarce, in this article we studied TiAlN/TiSiN coating magnetron sputtered on five different substrates, prepared with 1-, 2-, and 3-fold rotations. Cold-work tool steel (X153CrMoV12), hot-work tool steel (X37CrMoV5-1), plasma-nitrided hot-work tool steel, surgical stainless steel (X2CrNiMo18-15-3), and cemented carbide (WC/Co) were used as substrate materials. Three-dimensional stylus profilometry and atomic force microscopy were used for evaluation of micro and nano topography. The coated surgical steel has the highest roughness (Sa) which corresponds to the highest number of coating growth defects. However, the size of the individual growth defects was considerably smaller for this substrate than for other substrate materials. The observed difference is linked to differences in the concentration of specific carbides contained in a specific steel. Since different carbides have different polishing and ion-etching rates, coatings on different steels may have different concertation of defects. Columnar grain analysis revealed that coating on surgical steel exhibited the smallest column diameter (125 nm) and their highest uniformity. Column diameter on other substrates is around 215 nm, while hot-working tool steel exhibited the largest columns (235 nm). Such findings suggest that the same coating may exhibit different mechanical properties on different substrates. Coatings produced with the higher degree of rotation (2-fold, 3-fold) have fewer defects and a smoother surface. There was no clear trend between columnar grain size and the number of rotational degrees.

A Study of the Hydrodynamics Behavior of Cylindrical Gas-Solid Fluidized Beds for pharmaceutical material “Paracetamol “

The hydrodynamics behavior of gas - solid fluidized beds is complex and it should be analyzed and understood due to its importance in the design and operating of the units. The effect of column inside diameter and static bed height on the minimum fluidization velocity, minimum bubbling velocity, fluidization index, minimum slugging velocity and slug index have been studied experimentally and theoretically for three cylindrical columns of 0.0762, 0.15 and 0.18 m inside diameters and 0.05, 0.07 and 0.09 m static bed heights .The experimental results showed that the minimum fluidization and bubbling velocities had a direct relation with column diameter and static bed height .The minimum slugging velocity had an inverse relation with static bed height and a direct one with column diameter .There was no agreement between the experimental and calculated values of Umb for Di=0.0762m ,this was a result to the assumption used in the correlation development. The fluidization index values were around 1 in all cases and that proved that the material is of Geldart type B. There was not a significant dependence of fluidization index and slug index on static bed height and column diameter.